Field of the invention
The present invention relates to a scanning method and apparatus by an STA (station), and more specifically, to a method of performing active scanning by an STA and a method thereof.
Related Art
Recent wireless LAN techniques are evolving typically in three directions. In line with the existing wireless LAN evolution, an effort to further increase transmission speed includes IEEE (institute of electrical and electronic engineers) 802.11 ac and IEEE 802.11 ad. IEEE 802.11ad is a wireless LAN technique that adopts a 60 GH band. Further, as allowing for broader coverage of transmission than the existing wireless LAN, broadband wireless LAN utilizing a frequency band of 1 GHz or less nowadays gains popularity, which includes IEEE 802.11af utilizing the TVWS (TV white space) band and IEEE 802.11ah utilizing a 900 MHz band. These are primarily targeted for expansion of extended range Wi-Fi services as well as smart grid or broad area sensor networks. Further, the existing WLAN MAC (medium access control) techniques suffer from the problem that the initial link setup time is increased in some cases. To address such problem to allow an STA to quickly access an AP, there are rigorous activities for IEEE 802.11 ai standardization.
IEEE 802.11ai is an MAC technique that treats a swift authentication procedure to significantly save WLAN initial setup and association times and its standardization by a normal task group dates back January, 2011. For the purpose of a quick access procedure, IEEE 802.11ai is in discussion for process simplification in light of AP discovery, network discovery, TSF (time synchronization function) synchronization, authentication & association, process merge with higher layers, etc. Among them, ideas such as process merge utilizing piggyback of DHCP (dynamic host configuration protocol), optimization of the full EAP (extensible authentication protocol) using concurrent IP, and efficient selective AP (access point) scanning are being actively discussed.